[speeder]

If I was a school teacher teaching kids from various backgrounds in the USA, I would stress standard English like Sydney Poitier in "To Sir With Love" but also tell them that there is nothing wrong w slang as long as you know that you are speaking in slang. If it's the only way that you know how to speak, it will severely hold you back in life.

I don't think that accents are important, just the ability to speak and write standard English. I find regional accents interesting and charming if the person is well spoken. I believe that being fluent in your native tongue is among the biggest indicators of success in any business imaginable. And I include being a rap musician in that list.